In the July 22 issue of the journal Science, Caltech graduate student David Shuster and MIT assistant professor Benjamin Weiss (formerly a Caltech student) report that their studies of Martian meteorites demonstrate that at least several rocks originally located near the surface of Mars have been freezing cold for four billion years. Their work is a novel approach to extracting information on the past climate of Mars through the study of Martian meteorites. In fact, the evidence shows that during the last four billion years, Mars has likely never been sufficiently warm for liquid water to have flowed on the surface for extended periods of time. This implies that Mars has probably never had a hospitable environment for life to have evolved, unless life could have gotten started during the first half-billion years of its existence, when the planet was probably warmer.

For several years geologists have been gathering evidence indicating that Earth has gone into a deep freeze on several occasions, with ice covering even the equator and with potentially devastating consequences for life. The theory, known as “Snowball Earth,” has been lacking a good explanation for what triggered the global glaciations.

Ancient main belt asteroids identical in size to present-day asteroids in the Mars-Jupiter belt — not comets — hammered the inner rocky planets in a unique catastrophe that lasted for a blink of geologic time, anywhere from 20 million to 150 million years.

What’s it like to walk around on Mars in a space suit? No-one knows for sure. But geologist Dean Eppler has come as close as anyone. In this interview, he talks about his experience working in the Mark III experimental suit, as part of this year’s Desert RATS field season.

Chris McKay, a planetary scientist at NASA Ames Research Center, recently gave a public lecture, sponsored by the Planetary Society, about what scientists have learned about Titan from the Huygens probe. In this, the final part of a four-part series, McKay talks about the unsolved mystery of Titan’s ice rocks.

Meteor impacts are generally regarded as monstrous killers and one of the causes of mass extinctions throughout the history of life. But there is a chance the heavy bombardment of Earth by meteors during the planet’s youth actually spurred early life on our planet, say Canadian geologists

Scientists predict a near-miss when Asteroid 99942 Apophis passes Earth in 2029. An asteroid flies this close to the planet only once every 1,300 years. The chance to study it will help scientists deal with the object should it threaten collision with Earth.

Within the last few years, however, two simple chemicals intimately associated with life on Earth have been discovered on Mars. Large amounts of frozen water were discovered at the surface, and traces of methane appeared in the atmosphere.